The main objective of this study is to assess the ability of lipoic acid combined with omega-3 fatty acids in slowing cognitive and functional decline over 18 months in people with Alzheimer's disease (AD). Results from a pilot study conducted by our group showed that participants with probable AD randomized to lipoic acid (LA) plus omega-3 fatty acids (n=13) had significantly less decline in mean Mini Mental State Examination (MMSE) score and mean ADL score over 1-year compared to those in the placebo group (n=13). The proposed study will be a pilot trial designed to collect preliminary data on the effects of LA plus omega-3 fatty acids on cognitive function, ADL, and biomarkers of AD pathology. Data generated from this study would justify the design of a larger clinical trial to better assess the clinical effectiveness of LA plus omega-3 fatty acids in AD. The study is designed as a randomized, double-blind, placebo-controlled trial. Subjects 55 years or older diagnosed with probable AD, with mild to moderate cognitive impairment (MMSE 15-26) will be enrolled. One hundred subjects will be randomized to LA plus omega-3 fatty acids or placebo and will continue treatment for 18 months. The primary objective, Aim 1, is to assess treatment effect on slowing cognitive and functional decline (assessed by Alzheimer's Disease Assessment Scale - Cognitive Subscale and by Activities of Daily Living). Our hypothesis is that those randomized to receive LA plus omega-3 fatty acids will have less decline in cognitive function and ADL compared to the placebo group. Aim 2, is to collect preliminary data on changes in MRI total brain volume over time to evaluate this measure as a potential biomarker for treatment effect. Aim 3, is to collect preliminary data on a panel of serum and plasma biologic markers: tumor necrosis factor alpha;interleukin 6;osteoprotegerin;cholesterol;triglycerides;LDL;HDL;24S-hydroxycholesterol. Homeostasis Model of Insulin Resistance (HOMA-IR) will be used to measure treatment effects on insulin resistance. Associations between these markers and clinical outcomes will be determined. This study proposes to evaluate a novel treatment that has the potential to delay cognitive and functional decline in Alzheimer's disease. PUBLIC HEALTH RELEVANCE: This study will test the safety and effectiveness of lipoic acid plus omega-3 fatty acids in Alzheimer's disease. Because complementary and alternative medicine therapies are widely used in the U.S. and little is know about the safety and effectiveness of many of these therapies, it is an important public health issue to scientifically evaluate these therapies.